1. Field of the Invention
The present invention relates to a cooling device that is employed in applications such as cooling central processing units of personal computers or cooling power transistors used in amplifiers of acoustic apparatuses, relates to electronic apparatuses and acoustic apparatuses that employ the cooling device, and to methods for producing the cooling device.
2. Description of the Related Art
Advances in performances of central processing units (hereinafter called “CPUS” as required) have become considerable in recent years. On the other hand, the considerable advances in the performance of the CPUs have led to an increase in the amount of heat generated by the CPUs, and this larger amount of the heat eventually creates problems in that errors occur in the CPU.
CPUs are conventionally cooled by air-cooling by using a fan. However, the conventional air-cooling generally provides an insufficient cooling performance, and fans having higher cooling performances than the conventional fans may cause the more serious problem of noise.
Alternatively, cooling the CPU by circulating a cooling medium may be considered. However, sufficient cooling performance cannot be obtained by this technique. Further, such cooling-medium-circulating systems may increase the size of the apparatus configuration, thereby inhibiting its miniaturization.
These problems may also similarly occur in, for example, audio apparatuses that include power transistors requiring higher power, as well as in the personal computers.
Thus, the present inventors propose a technique of employing heat pipe as a means of cooling such apparatuses.
A heat pipe is a metal pipe having a capillary configuration on the inner wall of the pipe, and the interior of the pipe is substantially a vacuum but includes a smaller amount of water or substitutes for CFCs. When an end (vaporizing unit) of the heat pipe is heated by contacting a heat source, the liquid included within the heat pipe is evaporated, thereby absorbing heat as latent heat (vaporization heat). Then the vapor is transferred to a lower temperature unit (condensing unit) at a higher velocity (at substantially the sonic velocity), and the vapor is cooled to become a liquid again, thus emitting heat (heat emission by condensation latent heat). The liquid is then transferred back to the originating place through the capillary configuration (or by the force of gravity), and therefore, heat can be continuously transferred with high efficiency in this system.
However, the following problem occurs. Most of the heat pipes currently employed are small, and therefore, it is difficult for one heat pipe to sufficiently cool a large device such as the aforementioned CPU and audio apparatus, which consume a large amount of electric power, for example, 50 to 100 W or higher.
Further, another problem is that, since commonly used heat pipes often have a geometry in which the transfer channel for the operating medium of liquid/vapor phase is integrated with the vaporizing unit and the condensing unit, efficient cooling and heat releasing cannot be achieved when a specific object is cooled or when a specific arrangement of peripheral devices is used.